Update & Lifecycle

public class PlayerMovement : MonoBehaviour
{
  [SerializeField] private float speed      = 5f;
  [SerializeField] private float jumpForce  = 8f;
  private Rigidbody _rb;
  private Vector3   _moveDir;
  private bool      _jumpRequest;

  void Awake() => _rb = GetComponent<Rigidbody>();

  void Update()
  {
      // Input — đọc mỗi frame, lưu để FixedUpdate dùng
      float h = Input.GetAxisRaw("Horizontal");
      float v = Input.GetAxisRaw("Vertical");
      _moveDir = new Vector3(h, 0, v).normalized;

      if (Input.GetButtonDown("Jump")) _jumpRequest = true;
  }

  void FixedUpdate()
  {
      // Apply lực vật lý — không dùng Time.deltaTime ở đây
      _rb.velocity = new Vector3(_moveDir.x * speed, _rb.velocity.y, _moveDir.z * speed);

      if (_jumpRequest)
      {
          _rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
          _jumpRequest = false;
      }
  }
}

public class CameraFollow : MonoBehaviour
{
  [SerializeField] private Transform target;
  [SerializeField] private Vector3   offset = new Vector3(0, 5, -8);

  void LateUpdate()
  {
      // Chạy sau target.Update() — vị trí target đã finalize
      transform.position = Vector3.Lerp(transform.position,
          target.position + offset, Time.deltaTime * 5f);
  }
}

public class EnemyAI : MonoBehaviour
{
  private Transform _player;
  private float _attackCooldown = 2f;

  void Start()
  {
      _player = GameObject.FindWithTag("Player").transform;
      // AI tick mỗi 0.2s thay vì mỗi frame → tiết kiệm CPU
      StartCoroutine(AIUpdateLoop());
      StartCoroutine(AttackLoop());
  }

  // Chạy logic AI 5 lần/giây thay vì 60 lần/giây
  private IEnumerator AIUpdateLoop()
  {
      var wait = new WaitForSeconds(0.2f);
      while (true)
      {
          UpdatePathfinding();
          yield return wait;
      }
  }

  private IEnumerator AttackLoop()
  {
      while (true)
      {
          yield return new WaitForSeconds(_attackCooldown);
          if (Vector3.Distance(transform.position, _player.position) < 3f)
              Attack();
      }
  }
}